From owner-freebsd-security Tue Jul 10 9:44:49 2001 Delivered-To: freebsd-security@freebsd.org Received: from nsmail.corp.globalstar.com (gibraltar.globalstar.com [207.88.248.142]) by hub.freebsd.org (Postfix) with ESMTP id 76A4637B40F for ; Tue, 10 Jul 2001 09:44:40 -0700 (PDT) (envelope-from crist.clark@globalstar.com) Received: from globalstar.com ([207.88.153.184]) by nsmail.corp.globalstar.com (Netscape Messaging Server 4.15) with ESMTP id GG9NTO00.IZ1; Tue, 10 Jul 2001 09:44:12 -0700 Message-ID: <3B4B30E7.28607AEE@globalstar.com> Date: Tue, 10 Jul 2001 09:44:23 -0700 From: "Crist Clark" Organization: Globalstar LP X-Mailer: Mozilla 4.77 [en] (WinNT; U) X-Accept-Language: en MIME-Version: 1.0 To: Darren Reed Cc: freebsd-security@FreeBSD.ORG Subject: Re: FW: Small TCP packets == very large overhead == DoS? References: <200107100938.TAA13064@caligula.anu.edu.au> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: owner-freebsd-security@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.org Darren Reed wrote: > > In some mail from Crist Clark, sie said: > > > > The TCP segment is everything in the IP payload. An SYN segment is a > > TCP segment, but it carries no data and has a segment length of one (whee!). > > I can see that clearly in the RFC, and I think we all cab agree on that. > > However, I think that a SYN segment, which is all header, has a size greater > > than one. It looks more like 24-or-so bytes typically... or maybe it does not. > > I am looking for where (if anywhere) the specification comes out and says > > that segment "size" is the same as "length." Why isn't the MSS called the MSL > > after the RFC has gone to such pains to define "length?" > > Why can't a SYN segment be a TCP segment of length 0 ? > (with one phantom byte) For it is written, segment length The amount of sequence number space occupied by a segment, including any controls which occupy sequence space. ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ SYN A control bit in the incoming segment, occupying one sequence ^^^^^^^^^^^^^ ^^^^^^^^^^^^^^^^^^^^^^ number, used at the initiation of a connection, to indicate ^^^^^^ where the sequence numbering will start. -- Crist J. Clark Network Security Engineer crist.clark@globalstar.com Globalstar, L.P. (408) 933-4387 FAX: (408) 933-4926 The information contained in this e-mail message is confidential, intended only for the use of the individual or entity named above. If the reader of this e-mail is not the intended recipient, or the employee or agent responsible to deliver it to the intended recipient, you are hereby notified that any review, dissemination, distribution or copying of this communication is strictly prohibited. If you have received this e-mail in error, please contact postmaster@globalstar.com To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-security" in the body of the message